AVS 56th International Symposium & Exhibition
    Vacuum Technology Monday Sessions
       Session VT-MoA

Paper VT-MoA7
Total Pressure Measurement Integrated into a Ratiometric Partial Pressure Electrostatic Ion Trap Sensor

Monday, November 9, 2009, 4:00 pm, Room C1

Session: Pressure, Partial Pressure, and Flow Measurement
Presenter: P.C. Arnold, Brooks Automation, Inc.
Authors: P.C. Arnold, Brooks Automation, Inc.
G.A. Brucker, Brooks Automation, Inc.
Correspondent: Click to Email
A method of total pressure measurement concomitant with partial pressure analysis in a partial pressure analyzer ion trap will be presented along with representative construction geometries and data of the measurements. This combination of total pressure and partial pressures into a single sensor allows a more complete evaluation of the gas content of a vacuum chamber as well as its changing composition and absolute pressure. This method includes one ionization gauge structure which measures the pump-down progress to evaluate correct time of trap turn-on. Another ionization gauge structure is included that provides total pressure at high vacuum intermittently with the partial pressure scans. Ion traps are ratiometric devices that have an upper limit in the ion density that can be stored in their ionization trapping volumes. This limits the total number of ions measurable so that as pressure increases, no further absolute increase is observed in the sum of the amplitudes of individual gas species peaks, even though the differentiation in the various relative mass peaks continues to be readily seen.